Parser User Agent

Fast, accurate and free online parser user agent tool running directly in your browser.

Secure (SSL)

Client-Side Processing

100% Free

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Instructions

1

Enter data
Enter content, paste text or load a file from disk.
2

Click the button
The tool will immediately process your data in the browser.
3

Get the result
Copy the finished text or save the file to your device.

                                                function runTool() {

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                                                }

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Input data

125 characters

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Result

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User Agent Parser - Parse browser HTTP header

User Agent parserparses the User Agent string from HTTP headers and breaks it down into components: browser (name and version), operating system, device type (desktop, mobile, tablet, bot), rendering engine, and other information. Enter UA string or analyze your current one.

What is User Agent?

User Agent (UA) is the identifier sent by the browser (or other HTTP client) in the "User-Agent" HTTP header with each request to the server. It allows servers and web applications to identify the type of client making the query. Typical Chrome UA on Windows:Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36. History: UA started with a simple "Mozilla/1.0", but over the years it has grown into an indecipherable string of backward compatibility - hence all browsers include "Mozilla/5.0".

User Agent string structure

Despite the apparent chaos, UA has the structure:Mozilla/5.0- historical compatibility "token" (all modern browsers),(Windows NT 10.0; Win64; x64)- information about platform/OS in brackets,AppleWebKit/537.36 (KHTML, like Gecko)- rendering engine (Gecko = Firefox, WebKit = Safari, Blink = Chrome/Edge),Chrome/120.0.0.0- actual browser and version,Safari/537.36- Another compatibility token. The parser breaks down these tokens into readable data.

Uses of parsing User Agent

UA parsing is used for:Analytics- browser and visitor device statistics (Google Analytics, Matomo).Responsive serving- serving different code for mobile vs. desktop (although feature detection is better).Blocking bots- identification of crawlers (Googlebot, bots) or protection against scraping.Logging and debug- Debugging issues reported by specific users.A/B testing- Segment experiments by device or browser.Security- detection of suspicious UA (curl, Python requests, automatic attacks).

User Agent parsing problems

UA parsing is a known problem that is difficult to solve. Reasons: historical UA lying (browsers fake UA for compatibility - e.g. Edge includes "Chrome" in UA), fast pace of version changes (UA databases need to be updated regularly), custom UA (mobile apps, bots, scrapers use their own UA), lack of standardization (each manufacturer defines UA differently). Therefore, it is better to use feature detection (window.matchMedia) than UA sniffing to detect the device.

FAQ

How to download User Agent in JavaScript?

const ua = navigator.userAgent;. For details:navigator.userAgentData(new API, Chrome/Edge 90+) returns an object with brands (array of browser names and versions), mobile (bool), platform (string). Example:const { brands, mobile, platform } = navigator.userAgentData; console.log(brands[2].brand, brands[2].version);. The new API is better structured and harder to spoof.

How to check the User Agent of the current browser?

Several methods: 1) Type in the addressbar:about:blank→ F12 (DevTools) → Console → typenavigator.userAgent. 2) Enter in the addressbar:chrome://version/(Chrome) orabout:support(Firefox) - displays full version information. 3) Our parser automatically detects and displays the UA of the current browser.

How do bots and crawlers identify themselves through User Agent?

Googlebot:Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html). Bingbot:Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm). Other bots: contain the words "bot", "crawler", "spider", "scraper" or the name of the website. Googlebot verification: don't trust UA - check the client's IP via reverse DNS lookup to see if it comes from the Google range (*.googlebot.com).

How to change User Agent in the browser?

Chrome: F12 → three dots → More tools → Network conditions → disable "Use browser default" → enter custom UA. Or the "User-Agent Switcher" extension. Firefox: about:config → general.useragent.override. Applications: testing how the website looks from the perspective of another browser or device, testing responsiveness, bypassing specific UA blocks (not recommended).

Why do all browsers have "Mozilla/5.0" in UA?

Historical backwards compatibility. In the 1990s, Netscape Navigator (based on Mozilla) was dominant - servers served richer content to "Mozilla" users. Other browsers (IE, Opera) added "Mozilla/X.Y compatible" to UA so as not to get a "worse" version of the site. This custom has persisted for decades - today "Mozilla/5.0" means nothing and is present in all UA for compatibility with legacy servers.